This paper reports the findings of a numerical investigation on the droplet break-up in a microfluidic T-junction. The numerical flow visualization of the droplet formation process is validated with the experimental flow visualization. From the computational results, we show that the pressure profile of the dispersed phase and the continuous phase in the squeezing regime changes as the droplet break-up process proceeds. The assumption taken by other researchers that the dispersed phase pressure profile, during the droplet formation process at a T-junction, remains constant and only the continuous phase pressure changes according to the blockage of the channel is proved to be invalid. We provide new insights on the pressure difference between the dispersed phase and the continuous phase during the droplet break-up process and show that the minimum pressure difference happens at the last moment of the droplet break-up and not during the second and third stage of the droplet formation mechanism in the squeezing regime as suggested by other researchers.